Not much hot water, and flushing the tank produces clear, cold water

I moved into a condo about six months ago and hot water in my shower only ever lasts eight minutes, max. I was told that flushing the sediment from my electric water heater would probably fix it. When I started draining, I noticed the little bit that came from the pressure relief valve when I opened it was hot but water from the drain itself was cold. There was maybe a tablespoon of rusty water initially but the rest was crystal clear. I didn't drain the entire tank because I assumed clear water meant sediment isn't the issue (and also the drain is too close to the ground to fit a hose). I had only turned the water heater's breaker off a minute earlier so it didn't have time to cool down. Is one of the heating elements broken maybe?

The building is about 35 years old, and the water heater came with it, so I know nothing about its history. Both heating elements are set to 125 degrees Fahrenheit I am not a very handy person, is this a situation when I should call an expert or look into buying a new water heater?

Your lower element is most likely bad. That would explain both cold water on the bottom of the tank, and short time of hot water in the shower. Only the upper element is heating water. In effect giving you half of a tank of hot water.